Feeding mechanism for sewing machines



Feb. 8, 1944. N us 2,341,448

FEEDING MECHANISM FOR SEWING MACHINES Filed May 7, 1941 2 Sheets-Sheet 1 Wi /dfl f? I w v Q'wmm' NicholauT-st Feb. 8, 1944. v N.'KNAUS I FEEDING MECHANISM FOR SEWING MACHINES Filed May r, 1941 2 Sheets-:Sheet 2 Patented Feb. 8, 1944 UNITED STATES ATENr OFFICE;

FEEDING IVIECHANISM FORSEWING MACHINES Nicholaus Knaus, Newark, N. J.,assignor to The Singer Manufacturing Company, N. J a corporation of New Jersey Elizabeth,

Application May 7, 1941, l-am. 392.211

15 Claims.

This invention relates to feeding mechanisms for sewing machines and more particularly to that type of feeding mechanism known as a differential feed in which two work-feeding elements are adapted so to be actuated as to" exert unequal feeding actions on the work, thereby to either stretch or full the work as required.

The invention has as a primary object to provide an improved differential feeding mechanismments; and in which an individual adjustment is provided for varying the amplitude of movement of each feeding element, whereby each feeding element may be given either a greater or a less work-advancing movement than the other.

A further object of the invention is to provide improved means, readily accessible to the hand.

of the operator, for varying the action of that one of the feeding elem'ents which, in normal use, most frequently requires regulation.

With the above and other objects in View, as will hereinafter appear, the invention com-.

prises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily un-.

derstood by those skilled in the art.

Fig. 1 is a vertical sectional view illustrating a. portion of an overedge sewing machine embodying the present invention.

Fig. 2 is a perspective view of the improved feeding mechanism showing it operated from the main shaft of the sewing machine.

- Fig. 3 is a horizontal sectional view taken substantia'ily on the line 3-3 of Fig. 1.

Fig. 4 is a rear view, looking in the direction indicated by the arrow 4 in Fig. 1, of a portion, of the sewing machine and the improved feed-l ing mechanism.

Fig. 5 is a vertical sectional View taken substantially on the line 55 of Fig. 3. Fig. 6 is detail view, partly in section, illustrating the means for adjusting the connection between one arm of a feed-rocker and the auxiliary feed-bar.

Fig. 7 is a detail sectional view through the.

' ing movements.

of the feed-rocker arm and a link for actuating? the auxiliary feed-bar.

Referring more specifically source '.ofpower.

( not shown) forming and work-trimming mechanisms.

The improved feeding mechanism also is sup' ported by the machine frame and comprises a, horizontally disposed main feed-bar 6 carrying, at its forward end, a main feed-dog 1 which is' located andoperates wholly rearwardly of the:

stitching point. A horizontally disposed auxiliary feed-bar 8 extends parallel with the main feed-bar and carries at its forward end an? auxiliary feed-dog 9 which is-located and operates mainly in front of the stitching point. The main and auxiliary feed-bars are formed with fork portions 6 and 8*, respectively, which emthe main shaft 3.

nal'ed on a pin frame.

Endwise reciprocatory motions are transmitted. to the'feed-bars 6 and 8, and the feed-dogs carried thereby, from an eccentric [6 (Fig. 2);; se- 1 These endwise'i motions are effected in timed relation with the 1, up and down motions of the feed-bars under the influence of the eccentric lit to give to'the feed-dogs the conventional four-motioned feed- The feed-drive eccentric l61is. surrounded by a strap ll comprising one] 'e n'd" ofa pitman I8, theother end of 'Whichisc One.

nected to the free end ofa rock-arm l9 secured upon a'rock-shaft 29 journaled horizontally in the machine frame. Secured upon the shaft 20,

adjacent the end thereof remote fromthe rockel' arm l9, as by meansof set screws 2|, is a feed-I rocker 22. 'having, at its "Opposite ends, upstandr ing arr ns nland 24 adapted to be connected. to"

cured upon the main shaft 3.

to the drawings, the invention is illustrated as embodied in an over-edge sewing machin similar to that dis'-',' closed in my' United States Patent No. 2,238,796, Apr. .15, 1941, and comprising a main frame including a base I having upstanding portionsf 2 providing bearing in which is. journaled a rotary main shaft 3 driven from any suitable The frame supports stitch-, forming mechanism including a reciprocating curved eye-pointed needle! and looper mechan 1 ism (not shown), a work-trimming mechanism" and a. frame-hood 5 which. overlies and protects portions of the stitchef actuate the main and auxiliary feed-bars 6 and 8, respectively. The feed-rocker 22 is provided, below the shaft 28, with a weighted portion W designed to counterbalance the weight of the arms 23 and 24. Slidingly mounted on the arm 23 is a U-shaped strap 25 to which is pivoted, by means of a stud 26, one end of a link 2'! pivotally connected by a stud 28 to the main feed-bar 6. The strap 25 carries a clamp-shoe 29 engaging the rear edge of the arm 23 while the stud 26 carries a clamp-screw 30 adapted to engage the forward edge of the arm, thereby to draw the shoe into clamping contact with the arm to secure the strap in any adjusted position on the arm 23. The arm is of arcuate form, the axis of curvature being the center of the stud 28. From the foregoing it will be understood that the feed-rocker is oscillated about the axis of the shaft 23, and, through the arm 23, strap 25, stud 26 and link 21, transmits lengthwise movements to the main feed-bar 6. The amount of lengthwise movement transmitted to the feed-bar from any given degree of oscillation of the shaft 20, is dependent upon the setting of the strap 25 on the arm 23. This setting may be varied by loosening the clampscrew 30 and manually shifting the strap on the arm 23 after which it is again clamped by tightening the screw 39. v

The arm 24 is similar to the arm 23 and has slidingly mounted thereon a second U-shaped strap 3|, provided with a stud 3| which is connected by a link 32 with the auxiliary feedbar 8. The link 32 is connected to the auxiliaryfeed-bar by a pivot 33 which is substantially in alignment with the stud 28. Thus it will be'understood that the auxiliary feed-bar is given endwise movements by oscillation of the shaft 2|], the amount of movement for any given degree of oscillation of the shaft depending upon the setting of the strap 3| on the arm 24. As shown most clearly in Fig. '7, the strap 3| carries a shoe 50 having a convex face 50 which engages the concave edge of the arm 24, and a shoe having a concave face 5| which engages the convex edge of the arm. The shoe 5| also has on its outer face a concave surface 5| adapted to receive the periphery of a washer 52 journaled eccentrically on a clamp-screw 53 connecting the free ends of the strap 3|. The washer52 is provided with a plurality of radially extending holes 54 adapted to receive the end of a pin, or other element, by means of which the eccentric washer may be rotated on the screw 53, thereby to shift theshoe 5| toward the arm 24 and compensate for wear in the parts.

The eccentric l6 which oscillates the shaft 20 is preferably of the adjustable type in which the eccentric is mounted on a plate 34 slidingly fitted in a collar 35 secured to the main-shaft. The plate 34 is adapted to be shifted lengthwise, to vary the eccentricity of the eccentric l6 relative to the axis of the shaft 3, and thereby vary the degree of oscillation of the shaft 20, by rotation of an adjusting screw 36 carried by the collar 35, as is well understood.

In operation, the auxiliary feed requires adjustment more frequently than does the main feed. Therefore, means is provided whereby the operator may readily effect the required adjustments of the auxiliary feed. This means comrises an adjustable three-armed lever L of which one arm 31 is journaled upon a shoulder screw 38 threaded into the machine frame as shown most clearly in Figs. 2 and 3. A second arm 39 of the lever extends rearwardly and downwardly from the arm 31 and has secured to it at one side, by screws 40, a block 4| formed with an arcuate groove 42 which faces the arm 24 and receives a stud 43 carried by and projecting laterally from the strap 3|. The third arm 44 of the lever L extends upwardly to a position immediately beneath the frame-hood 5 and has its upper end in vertical alignment with a slot 45 in said hood. Threaded into the upper end of the arm 44 is the shank of a clampscrew 46 which extends through the slot 45 and has a shoulder 41 adapted to bear upon the frame-hood and a knurled portion 48 by which the screw may be turned to clamp the lever L in its various positions of adjustment. The screw 46 forms, in effect, a portion of the lever L and therefore may be considered to be a part thereof.

The center about which the arcuate groove 42, in the block 4|, is formed is located materially below the axis of the pivot screw 33 for the lever L and in the uppermost position of the lever that center is adjacent the axis of the shaft 20. Therefore swinging of the lever L about its pivot will cause the walls of the groove 42 to exert a cam action on the stud 43 thus shifting the strap 3|, and the attached end of the link 32, lengthwise of the arm 24 thereby varying the extent of endwise movement transmitted to the auxiliary feedbar 8.

In any given setting of the adjustable eccentric l6 rotation of the main shaft 3 will cause the shaft 20, and the feed-rocker 22 attached thereto, to be given a definite number of degrees of 0s cillation. With the straps 25 and 3| adjusted to their uppermost positions on the arms 23 and 24 the feed-bars 6 and 8 will be given the maximum feed strokes available under that particular setting of the eccentric, which feed strokes will be equal, thereby giving to the main and auxiliary feed-dogs synchronous movements of equal amplitude. If either the strap 25 or the strap 3| is then adjusted downwardly on its supporting arm the specific feed-bar; connected with that strap will be given a reduced movement. The lever L affords convenient means whereby the operator may vary the position of the strap 3|, thereby to either increase or decrease the feeding stroke of the auxiliary feed-bar. Inasmuch as the strap 25', connected with the main feed-bar, requires only infrequent adjustment, the adjusting means therefor hereinbefore described will suffice. In practice, the strap 25 is usually secured to the arm 23 at an intermediate point thereon so that by manipulation of the lever L the auxiliary feed-dog may be given either a greater or less amount of movement than the main feed-dog;

In the sewing of certain materials, such for example as' rayon it is desirable that the material be stretched during sewing. When sewing such materials the auxiliary feed-dog 9 is given a shorter feedingstroke than the main feed-dog In sewing stretchy materials, such for example as knit goods, it is desirable that the material be fulled or crowded in ahead of the stitching point. This is effected by giving the auxiliary feed-dog a greater feeding movement than the main feed-dog.

From the foregoing it will be apparent that this invention has provided an improved feeding.

dog. It will also be apparentthat the invention has provided simplified means, readily accessible to the hand of the operator, for regulating the action of the auxiliary feed either While the machine is at rest or in operation.

Having thus set forth the nature of the invention, what I claim herein is:

. 1. In a sewing machine having main and auxiliary feeding mechanisms including main and auxiliary feed-dogs arranged in tandem with one of said feed-dogs located mainly in rear of the stitching point and the other feed-dog located mainly in advance thereof, the improvement which consists in the provision of a single means for varying the action of both feeding mechanisms, and individual means for selectively to actuate both of said feeding mechanisms,

means for varying the eccentricity of said eccentric thereby to vary the action of both of said feeding mechanisms, and individual means for selectively varying the action of each of said feeding mechanisms.

3. A sewing machine having main and auxiliary feed-bars, a feed-dog connected to each of said feed-bars, a feed-rocker having two arms each connected to actuate oneof said feed-bars, and means to vary the point of connection between each feed-bar and its connected arm thereby'individually to vary the feeding stroke transmitted to each of said feed-bars by said feed-rocker.

4. A sewing machine comprising a rotary driveshaft, a rock-shaft, means connecting said driveshaft with said rock-shaft whereby oscillations are transmitted to the latter from the former, a two-armed feed-rocker secured to said rockshaft, a main feed-bar connected with one of the arms of said feed-rocker, an auxiliary feed-bar connected with the other arm of said feed-rocker, and individual means for adjusting the connection between each of said rocker arms and its associated feed-bar thereby selectively to vary the extent of movement of each of said feed-bars under the influence of said feed-rocker.

5. A sewing machine comprising a rotary drive-shaft, a rock-shaft, means for oscillating said rock-shaft from said drive-shaft, a feedrocker secured upon said rock-shaft and provided with two arcuate arms, a main feed-bar, an auxiliary feed-bar, a link pivotally connected to each of said feed-bars and adjustably connected with one of said arms, the center of curvature of each of said arms being located substantially at the point of connection between its associated link and the feed-bar actuated thereby, and means to vary the point of connection of each of said links with its associated rocker arm to vary the amount of endwise movement transmitted to the connected feed-bar.

6. A sewing machine comprising a rotary drive-shaft, an eccentric thereon, a rock-shaft, a rock-arm thereon, a pitman connecting said eccentric with said rock-arm thereby to efiect oscillations of said rock-shaft from rotations of of said eccentric to vary the degree of oscillation ofsaid rock-shaft, a feed rocker secured uponsaid rock-shaft and provided with two arms, a main feed-bar, an auxiliary feed-bar,v

two links each having one end slidably connected with one of said arms and its other end pivotally connected 'toone-of said feed-bars for transmitting endwise reciprocation to said feedbars from the oscillatory motions of saidfeedrocker, and individual'means for adjusting the point of comiection between each of said links and its associated rocker-arm thereby to vary the amount of endwise movement transmitted to the feed-bar connected therewith.

'7. A feeding mechanism for sewing machines comprising a feed-rocker having two arms, a

member slidably mounted on one of said arms,

means for oscillating said feed-rocker, a main feed-bar adjustably connected with the other of said arms, an auxiliary feed-bar, a link pivot.- ally connected at one end to said auxiliary feedbar and at its other end to said member to transmit reciprocating motions to said auxiliary feed-bar from the oscillatory motions-of said feed-rocker, and means including a manually adjustable lever operatively connected with said member for adjusting the position of said member on the first mentioned arm thereby to vary the movement transmitted to said auxiliary feed-bar by said feed-rocker.

8. In a sewing machine having a frame, rock-shaft journaled insaid frame and means to oscillate said rock-shaft; a feeding mechanism comprising a feed-rocker secured-upon said rockshaft and having a pair of spaced arms, a main feed-bar operatively connected with a first one of said arms, an auxiliary feed-bar, a link pivotally connected at one end to said auxiliary feedbar and slidingly connected at its other end with the second one of said arms, a feed-regulating lever pivotally mounted on said frame and operatively connected to shift the connection between said auxiliary feed-bar and said second arm thereby to vary the extent of movement transmitted to said auxiliary feed-bar by said feed-rocker.

9. In a sewing machine having a frame and a drive-shaft journaled therein; a differential feeding mechanism comprising a two-armed feed-rocker, means actuated by said drive-shaft for oscillating said feed-rocker, main and auxiliary feed-bars, a feed-dog carried by each feedbar, means including a manually actuable clamp for adjustably connecting said main feed-bar with one of the arms of said feed-rocker, means including a link pivotally connected at one end to said auxiliary feed-bar and having its other end slidingly connected to the other arm of said feed-rocker for transmitting endwise reciprocations to said auxiliary feed-bar, and a lever pivotally mounted on said frame and operatively connected with said link and having a portion readily accessible to the operator for adjusting the point of connection of said link with said other rocker-arm thereby to vary the amplitude of motion transmitted to said auxiliary feed-bar by said feed-rocker.

10. A difierential feeding mechanism for a sewing machine having a frame, comprising a rock-shaft journaled in said frame, means to oscillate said rock-shaft, a feed-rocker secured upon said rock-shaft and having a pair of arms, main and auxiliary feed-bars each operatively said' drive-shaft, means to 'vary the eccentricity connected with one of said arms, the connection between the auxiliary feed-bar and one of said arms including a member slidingly mounted on the arm, and feed-regulating means including a three-armed lever having one arm pivotally connected to said frame, the second arm being operatively connected with the member slidingly mounted on one arm of the feed-rocker and the third arm extending to a position where it is readily accessible to the operator for manual manipulation to vary the actionof said auxiliary feed-bar.

11. A difierential feeding mechanism for a sewing machine having a frame, comprising an oscillatory feed-rocker provided with a pair of arms, a main feed-bar adjustably connected to and actuated by one of said arms, a member mounted on and adjustable lengthwise of the other of said arms, an auxiliary feed-bar operatively connected with said member for actuation by said feed-rocker, means to shift said member on said arm thereby to vary the action of said auxiliary feed-bar, said means including a manually adjustable lever mounted on said frame and operatively connected with said member, and means to lock said lever in its various positions of adjustment.

12. A differential feeding mechanism for a sewing machine having a frame, comprising an oscillatory feed-rocker provided with a pair of arms, a main feed-bar actuated by one of said arms, a member mounted on and adjustable lengthwise of the other of said arms, an auxiliary feed-bar operatively connected with said member for actuation by said feed-rocker, means to shift said member on said arm thereby to vary the action of said auxiliary feed-bar, said means comprising a manually adjustable lever pivoted on said frame and having a portion readily accessible to the operator, a cam connection between said lever and said member whereby adjustment of said lever shifts said member and varies the acton of said auxiliary feed-bar, and means to lock said lever in its adjusted positions.

13. A sewing machine comprising a frame, main and auxiliary feed-bars supported thereon, a feed-dog carried by each feed-bar, an oscillatory feed-rocker having a pair of arms each operatively connected with one of said feed-bars for giving to said feed-bars endwise reciprocations, means for varying the connection between the auxiliary feed-bar and its associated rocker-v arm thereby to vary the extent of reciprocation of said auxiliary feed-bar, said means comprising a member slidably mounted on said associated rocker-arm and connected with the auxiliary feed-bar, a stud projecting from said member,

a manually actuable feed-regulating lever piy-.

otally mounted on said frame, a cam carried by said lever and engaging said stud, means for turning said lever about its pivot to cause said cam to shift said stud and member on the associated rocker-arm, and means for locking said lever in its adjusted positions,

14. A sewing machine comprising a frame, main and auxiliary feed-bars supported thereon, a feed-dog carried by each feed-bar, a slotted frame-hood secured to said frame and overlying said feed-bars, an oscillatory feed-rocker having a .pair of arms each operatively connected with one of said feed-bars for giving to said feed-bars endwise reciprocations, an adjustable connection between one of said rocker-arms and the auxiliary feed-bar whereby the extent of movement transmitted to said auxiliary feed-bar by said feed-rocker may be varied, means including a plural-armed feed-adjusting lever pivotally mounted on said frame and having one portion engaging the adjustable connection between the feed-rocker and the auxiliary feed-bar and another portion projecting through the slot in said frame-hood for easy engagement by the operator, and means to lock said lever in its adjusted positions.

15. In a sewing machine having main and auxiliary feed-dogs and means to impart the usual rising-and-falling movements thereto, the improvement which consists in the provision of a feed-advance actuating element common to both feed-dogs with adjustable means to vary its amplitude of motion, and an individually adjustable branch connection from said actuating element to each of said feed-dogs, respectively, to vary the amplitude of motion imparted thereto by said element.

NICHOLAUS KNAUS. 

